In the safety and guard industry, there are high requirements on a high-definition video image, and particularly the requirements on 720p, 1280p and other high-definition video formats have gradually evolved as a standard in the industry. At present a high-definition spherical video camera also has to accommodate the demand for a high-definition video. The high-definition spherical video camera is generally embodied in the form of products including a network spherical video camera and a Serial Digital Interface (SDI) spherical video camera, and in order to enable a video camera core inside the spherical video camera to be rotated horizontally over 360 degrees and vertically over 90 or 180 degrees arbitrarily, the video camera core and the master control board are connected by an electrically-conductive slip ring to thereby guarantee the reliability in electrical connection of the video camera core during rotation. At present the following two transmission schemes are generally adopted for 720p, 1280p and other high-definition video formats:
Firstly a video signal output by the video camera core is converted into a High Definition-Serial Digital Interface (HD-SDI) signal and transmitted to the control board through the electrically-conductive slip ring, but the clock frequency of the HD-SDI signal is approximately 1.485 GHz, so the digital signal at the high clock frequency can not be transmitted over a conventional electrically-conductive slip ring, therefore an expensive and process-complicated specialized electrically-conductive slip ring has to be customized, and the transmitted signal may be susceptible to interference.
Secondly the video signal output by the video camera core is converted into a multi-channel Low-Voltage Differential Signaling (LVDS) signal transmitted to the control board through the electrically-conductive slip ring by transmitting the differential signal over a plurality of channels for the purpose of sharing the amount of data. Taking five channels as an example, the signal is transmitted at the clock frequency of 27 MHz, but the frequency of the transmitted signal is still high and susceptible to interference, and there is a high requirement on the performance of the electrically-conductive slip ring. Moreover a plurality of transmission cables added as a result of a significant increase in number of channels and of an externally applied synchronization clock may also result in a significant increase in volume of the electrically-conductive slip ring and consequentially an increase in cost thereof. As a result, the structure of the spherical video camera may be restricted by the volume of the electrically-conductive slip ring and consequentially can not be minimized.
In summary, the electrically-conductive slip ring characterized by discontinuous impedance and a large number of joints thereof may impose a considerable negative influence upon the integrity, the quality of signal and other aspects of a high-frequency digital signal or an analog signal, thus degrading the accuracy of transmitted video images and consequently resulting in blocking, dithering, a frame loss and other problems of the images. Moreover the volume of the spherical video camera may be limited.